The Postbaccalaureate Research Education Program (PREP) at Johns Hopkins University School of Medicine, now in its fourth year, proposes to select six recent college graduates each year from backgrounds traditionally underrepresented in science who desire PhD research careers and will benefit substantially from a year of intensive research experience and custom mentoring. We prepare these promising students for entry into rigorous PhD training programs and long-term success. Scholars visit Hopkins in April for a two-day Mentor- Matching event to interview potential mentors in their field of interest, and are matched with an enthusiastic Research Mentor. RESEARCH: Scholars learn, design, conduct and analyze hypothesis-driven experiments in the mentor's lab, and participate in weekly lab meetings, journal clubs and departmental research seminars, and a national conference. `Project Meetings' (mini-thesis meetings) are a key new feature: each Scholar invites two subject-expert faculty in addition to their Research Mentor and PREP Director to three meetings during their first year. Scholars prepare a written proposal for a one-hour discussion with their committee, and benefit from their own support network of scientific mentors. Project Meetings have increased faculty awareness of this program; 62 faculty are ready to serve as research mentors or advisors for PREP Scholars. PREP COMMUNITY: Scholars gather for a two-hour `Chalktalks' event each month with dedicated Peer Mentors (ten underrepresented minority PhD students and postdoctoral fellows) to practice talking science, ask questions and get advice within our PREP community. Scholars also mix with PhD students at events including a vibrant annual PhD program retreat. PROFESSIONAL TRAINING: Scholars participate in Research Ethics workshops taught by the School of Medicine, an NSF (National Science Foundation) graduate fellowship workshop, and Writing & Peer-Editing Workshops taught by the PREP Director. PERSONAL GROWTH: The Director and Scholar create an individual development plan (IDP) to set goals and strengthen specific areas needed to be competitive for PhD success. IDPs can include graduate-level coursework, practice interviews, workshops (e.g., critical analysis, personal finances, time management, communication) and GRE/MCAT test preparation funded by our institution. Scholars meet individually with the Director for one hour every month, and informally as needed. This program will be evaluated yearly by direct feedback and by the Hopkins Office of Assessment & Evaluation, including pre- and post-assessment of confidence in 21 areas of scientific competence (self-efficacy). Success will be defined as the entry of at least 75% of PREP scholars into rigorous PhD or MD/PhD programs nationwide, within two years of starting PREP. Our actual 2-year success rate so far is 92%, and two Scholars were awarded National Science Foundation graduate fellowships in 2018. By preparing outstanding URM trainees for PhD or MD/PhD careers, this program is having a positive impact on PhD student diversity and fostering a culture of inclusion at Johns Hopkins and nationwide.